Yo-yo's, Moment of Inertia, and Rotational Potential Energy

[conrthomas]

See the attached PDF document, all information is given and the help I need is on number 2-5, which is all one problem. I do already know that you have to do 2, then 5, then 3, then 4. Between 30 of my friends and I, we cannot get it.

Thanks in advance.

 

[ashishsinghal]

ok let's start with the second question
you must understand the body is doing both translational motion.
the axis here is the line along which it is rotating. it is passing through three cylinders
for a cylinder MI =(mr^2)/2
you need to calculate for each cylinder and then add these

 

[ashishsinghal]

for third and fourth questions:
when you have found the MI then:
draw the fbd...
there are two forces on the object- weight and tension here tension in unknown
you know one thing - since there is no slipping the point of object in contact with rope will have zero acceleration.
from this much information you can find tension and acceleration

 

[ashishsinghal]

you can easily solve the fifth question once you have solved the third and fourth

 

[ashishsinghal]

the order was not correct
you cannot do 5 without knowing acceleration